1. Technical Field
The present disclosure relates to field emission electron source and field emission device using the same, and particularly relates to a carbon nanotube based field emission electron source and field emission device using the same.
2. Description of Related Art
Carbon nanotubes feature extremely high electrical conductivity, very small diameters (much smaller than 100 nanometers), large aspect ratios (i.e. length/diameter ratios greater than 1000), and a tip-surface area near the theoretical limit (the smaller the tip-surface area, the more concentrated the electric field, and the greater the field enhancement factor). These features tend to make carbon nanotubes ideal candidates for electron emitters of field emission device.
Two ways to use the carbon nanotubes in the field emission device are: directly growing a carbon nanotube array on a substrate by using chemical vapor deposition (CVD) methods to be the field emitters; and mixing carbon nanotube powder with a binder to form a carbon nanotube slurry, and coating the carbon nanotube slurry on a conductive base to be the field emitters. However, the carbon nanotubes have the same height in the carbon nanotube array, which induces a shielding effect between the adjacent carbon nanotubes and an emission mainly at the edge of the carbon nanotube array. Therefore, the field emission efficiency of the carbon nanotube array is relative low. The carbon nanotube slurry is difficult to be coated on the conductive base as a uniform layer, which induces a non-uniform electron emission.
What is needed, therefore, is to provide a field emission electron source and field emission device using the same which has a relatively good field emission performance and easily to be manufactured.